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Tue Nov 03, 2020 12:29 pm

I have conflicting research on rotor min. thickness. These are stock. Some manuals say 8.5 mm and others say 10 mm. Would love to resurface the german ones that are on my car now...but not sure if I can. I am at 10 mm on both of them currently.
Bill

Tue Nov 03, 2020 1:34 pm

Pepperbilly wrote: I have conflicting research on rotor min. thickness. These are stock. Some manuals say 8.5 mm and others say 10 mm. Would love to resurface the german ones that are on my car now...but not sure if I can. I am at 10 mm on both of them currently.
Bill

I will have to consult my book to make sure that the earloer rotors ....1969 to August of 1972.....did not have a thinner rotor. But.... on the 412 ...August of 1972 onward.....the rotors were 11mm new with a WEAR limit of 9.5mm.....but a MACHINE TO limit of 10mm.

I used to work hard to try to save German rotors that were still 10.5mm or thicker. Its not really worth it,when you can buy EXCELLENT quality new German made rotors from Sebro or Zimmerman....for roughly 2X the cost of having a pair of old rotors turned. Ray

Tue Nov 03, 2020 5:46 pm

Yeah, I don’t think I am going to mess with my old marginal rotors. If quality ones are still available in the market I will go with that. No need to compromise on this restoration.
Bill

Tue Nov 03, 2020 7:06 pm

Pepperbilly wrote: Yeah, I don’t think I am going to mess with my old marginal rotors. If quality ones are still available in the market I will go with that. No need to compromise on this restoration.
Bill

OK....looking at the Haynes for 411/412 and the Haynes for Porsche 914 (same brakes) and the "without Guesswork" book for type 3 and 4.....

1. Just for basic info....There were two different sets of brakes for 411/412/914 cars.

A. those from 68 to August of 1972 (start of 1973 model year) ....and from August of 1973 to 1975.

Some books stupidly fowl things up by calling it "to July of 1972"...meaning end of July...which is August. :roll

The parts in these two brake sets are not interchangeable. They had a different roto, spindle and hub, caliper and pad. This goes for both the 411/412 and 914 cars.

If you do not know what you are looking at....most people do not know any difference between these two brake sets.

B. The earlier type 4 brake set.....1968 to the end of the 1972 model year....were used complete....on the last two years of the type 3. So...late type 3 is the same as early type 4.

On both early and late type 4 brake discs.....the new dimension is 11mm. The machine limit is 10mm. The limit from natural wear is 9.5mm.

Some of the books get confused....because type 3....up TO 1972 model year...used a different caliper with a THINNER disc. It was 9.5mm new with a machine limit of 8.5mm and a natural wear limit of 8.0mm.

No type 4 uses these thin type 3 rotors.

This confusion gets propagated...because you hear so many type 3 people stating "the type 3 uses the same brakes as the 412 and 914"....which is not quite true. The last TWO YEARS of type 3....use the same brake parts as the EARLY 411 and 914.

So...places you can get new ones.

PMB performance is a go to place. They specialize in Porsche and Mercedes Benz. But...they have early and late, high quality rotors, caliper rebuild kits and pads....for BOTH eras of 411/412 and 914.

These rotors are a little pricy...and pricing has gone up this year like everything else...but they are made in Germany Sebro brand. Excellent quality
https://www.pmbperformance.com/catalog/item/1925563/1475454.htm

Same rotor and price here at Autohaus AZ
https://www.autohausaz.com/pn/411407075B

Pelican has the rotor for $4 more. They also have Centric for about $11 less. Centric is a very competent rotor. Well made.
https://www.pelicanparts.com/catalog/SuperCat/5893/POR_5893_BRKDSC_pg1.htm#item1

Automobile Atlanta has the same brake disc for $80.
http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=porsche-914-parts&section=602-00

Rockauto shows only one disc brand in stock right now. Its a Raybestos. Its listed under economy...which it really is not. Its just that what they currently list under premium....are exotic drilled/slotted or coated stuff from dynamic friction.
Both Raybestos and Centric are listed under economy...which they are not. They are both good basic stock level. The Raybestos is $55 each.

Personally...if you are spending $110 + tax and shipping....I sy just spend $60 more and get the Sebro. But the Raybestos will do just fine.

What CIp-1 sells...will still cost you $72...and I have no idea where that is made. At least Centric is cast in Ohio.
https://www2.cip1.com/SearchResults.asp?Cat=1200

Ray

Tue Nov 03, 2020 7:27 pm

Yep, this is the confusion I was seeing in the books. Thanks for the explanation and directing me to the good rotors. I will also be using your wonderful tutorial for rebuilding my calibers.
Bill

Wed Nov 04, 2020 6:49 pm

I found this stamping on the rotor edge with the rotors still on the car. You can clearly make out made in West Germany and mm min th. 9. 8? mm. The 8 confuses me... or is it an 8? I can’t remember if these are the originals... which I highly doubt because the 412 had 126,000 miles when stored away years ago.
Bill

Wed Nov 04, 2020 7:14 pm

Pepperbilly wrote: I found this stamping on the rotor edge with the rotors still on the car. You can clearly make out made in West Germany and mm min th. 9. 8? mm. The 8 confuses me... or is it an 8? I can’t remember if these are the originals... which I highly doubt because the 412 had 126,000 miles when stored away years ago.
Bill

Just to be sure what you have....show us a picture of the outside of the brake rotor hub where the cap snaps on it.

Its very possible...that either your car was on the fringe/line between the early and late models....or just as likely....that 411 brakes were swapped onto it.

Its simple to do. Just take the knuckles/spindles...with the rotor and caliper and they swap right on with no other changes.
I actually drove on a set of them in one of my 412' for two years because I had them and they were in better shape than mine.

A view of the rotor hub will tell the story.

Here is the early rotor up to August of 1972

These early rotors are the ones that "might" advertise an 8mm minimum wear...if it was originally slated as a type 3 rotor.

Here is the late rotor from August 1972 and onward.

Notice the extra ring around the outside center of the late rotor above.

The one thing I do not know...is if the very early type 3 rotor was interchangeable with the later type 3 rotor....which would make it interchange with early type 4 as well.

Ray

Wed Nov 04, 2020 7:40 pm

Ray,
I have the extra ring on mine which is a centering ring for the wheel as I understand it. If these rotors are still good I will use them but want to make sure this will be correct. Never thought anything so simple would be so complicated...lol!
Bill

Wed Nov 04, 2020 8:07 pm

Pepperbilly wrote: Ray,
I have the extra ring on mine which is a centering ring for the wheel as I understand it. If these rotors are still good I will use them but want to make sure this will be correct. Never thought anything so simple would be so complicated...lol!
Bill

Yes...then you have the 1973 and on brake system.

I have no idea why the books state 11mm new (which is true) and 10mm machined( I get that)...and 9.5mm natural wear ( I get that too).

I have no idea why some manufacturers state minimum 9mm.

When I get back home tomorrow night...I will look at my rotors. I have two different brands. I got them both NOS year ago. They only have a few thousand miles on them and all of the markings are clear.

One is an ATE and the other is Zimmerman.
Ray